Bike riders risk kidney, genital injuries: study

A jogger and a cyclist make their way around Lake Michigan in Chicago, March 21, 2014. (REUTERS/Jim Young)

Biking has plenty of health benefits, but riders also run the risk of an injury to the kidney or genitalia, according to a new study that found kids sustain about 10 times as many of these injuries as adults.

Cyclists are often correctly encouraged to wear a helmet, but the study shows head injuries aren't the only ones they should be concerned about, researchers write in the journal Injury Prevention.

"We were surprised that there were so many injuries related to bike riding," co-author Dr. Benjamin Breyer, a urologist at the University of California, San Francisco, said in an email.

The researchers analyzed data that had been collected by the National Electronic Injury Surveillance System between 2002 and 2012. The system includes information on patients who came to the 24-hour emergency rooms of about 100 hospitals nationwide, including eight children's hospitals.

Breyer and his team separated the patients by age group and looked at whether each person had been subsequently admitted to the hospital, which would indicate a relatively severe injury. They excluded injuries that had been caused by a collision with a car.

The study did not examine the severity of injuries in more detail or whether the patients had required a follow-up visit with their doctor afterward.

An average of about 4,000 people sustained bicycle-related kidney or genital injuries during each year of the study, the authors found. They also discovered that children came to the ER for bicycle-related kidney or genital injuries about 10 times more often than adults: about 448 of every 100,000 children, as opposed to 53 of every 100,000 adults, presented to the ER each year for such injuries.

Still, adults' injuries more often required hospital admission. About 12 percent of the adult ER visits in the study led to a hospital admission, compared to 7 percent of children's visits.

Boys and men accounted for 61 percent of injuries.

About 70 percent resulted from direct contact with the bike - as opposed to hitting the ground - and nearly half of the overall injuries were due to contact with the top tube, which runs between the base of the seat and the handlebars. Males were more likely than females to be injured by the bike's handlebars.

Despite these data, the authors called the paper "exploratory," emphasizing that it shouldn't necessarily lead to changes in safety precautions.

"Our data hasn't informed prevention strategies yet," said Breyer.

Although changes in a bicycle's design could potentially prevent some injuries, "you can't figure that out with this kind of study," he said.

Some experts argued that biking holds inherent risks, and that making changes to bicycles in light of so few major injuries isn't necessary.

"This particular study, if anything, shows that the vast majority of people who come to the ER come for minor injuries," said Landon Trost, a urologist at the Mayo Clinic in Rochester, Minnesota.

Although the study's authors argue that changing the angle of the top tubes on women's bikes might thwart injuries, Trost said, many bicycles already have this feature. And further safety measures seem excessive, he said.

"Should kids wear an athletic cup? Should we have airbags on handlebars?" Trost said.

The experts still agree on one thing: the importance of common sense and a good helmet.

"Riding your bike safely is the most important thing. Wear a helmet, follow the rules of the road, and be alert and be visible," Breyer said.